DCHP-1 Online
yellowlegs [from the yellow stripe down the sides of the breeches] Slang, Derog. 
n. pl. a member of the Royal Canadian (formerly, North West) Mounted Police.
See also: Mounted Policeman Royal Canadian Mounted Police
- 1918 "Oh, you Harry! Say, wha's dat dere wit de yaller laigs?"
- 1955 . . . the American who had been in the fight, and who was now keeping lookout, pulled his bullet head in suddenly and yelled "Yellowlegs."
- 1959 "You're her brother and I'm your friend. Even the damned yellow legs can't break that."
- 1918 "Oh, you Harry! Say, wha's dat dere wit de yaller laigs?"